Automated laboratory systems utilize standardized carrier units which travel about conveyors or are otherwise transported throughout a laboratory, to convey individual specimen containers to various testing apparatus. Examples of such specimen carriers may be found in U.S. Pat. No. 5,589,137 to Markin et al., U.S. Pat. No. 5,417,922 to Markin et al., and U.S. Pat. No. 5,427,743 to Markin. Each of the specimen carriers noted above includes a plurality of openings having various depths and sizes for the receipt of a variety of sizes of specimen containers, including test tubes, vials and the like.
Robotic equipment utilized to retrieve an individual specimen container from a specimen carrier unit is programmed to move a pair of grasping jaws to a predetermine location, clamp the jaws together about the specimen container located at the location, and then raising and transporting the specimen container to the desired location. However, the use of a specimen carrier which provides a plurality of locations in which the specimen container may be located and/or a plurality of sizes of specimen container, causes a problem for such robotic equipment. It is difficult and complicated to program a piece of robotic equipment to detect the specific location of a specimen container within a specimen carrier, center the grasping arms at the sensed location of the container, and then grasp and remove the container. In order to assure that the robotic arm will securely grasp and remove the specimen container, the container must be precisely positioned at a single predetermined location programmed into the robotic arm.
This also can be a problem with a specimen carrier having only a single opening for a specimen container. If the carrier is not stopped and positioned precisely, the robotic arm may not properly grasp and remove a specimen container from the carrier, or may completely miss the container.